1,2,4,5,8,10 16,20,40,80

Multiples
1X80=80
2X80=160
3X80=240
4X80=320
5X80=400
6X80=480
7X80=560
8X80=640
9X80=720
10X80=800
Factor Tree
80
40 2
^ \
20 2 2
^ \ \
10 2 2 2
^ \ \ \
5 2 2 2 2 = 2⁴ x 5